The Kiyosu Conference

The Honnō-ji Incident and the Question of Oda Succession

On the 2nd day of the 6th month of Tenshō 10 (June 21, 1582), before dawn, Oda Nobunaga was lodging at Honnō-ji in Kyoto on his way to a campaign in the Chūgoku region when he was attacked by his retainer Akechi Mitsuhide in an act of betrayal and took his own life. Oda Nobutada, Nobunaga's heir and then head of the Oda clan, was also surrounded by Akechi's forces at the Nijō New Palace in Kyoto on the same day and committed suicide. With the simultaneous loss of Nobunaga and Nobutada, the Oda clan was pressed to determine quickly its successor and the disposition of its domains.

Mitsuhide was defeated by Hashiba Hideyoshi at the Battle of Yamazaki on the 13th day of the same month and was killed, and Hideyoshi's influence within the Oda clan rose sharply. Amid this situation, a council of senior retainers was convened at Kiyosu Castle in Owari Province to discuss the future of the Oda clan. Nobunaga's sudden death had abruptly removed the core of the Oda regime, which had been taking shape from the Kinai to the Tōkai region, and unless the control of the clan and the allocation of its domains were settled quickly, the situation could invite intervention by neighboring forces or a split within the clan.

The Convening of the Kiyosu Conference

Kiyosu Castle was located at Kiyosu in Kasugai District, Owari Province (present-day Kiyosu City, Aichi Prefecture), and was the stronghold Nobunaga had used to govern Owari before he moved his base to Gifu Castle and Azuchi Castle. For the Oda clan after the deaths of Nobunaga and Nobutada, the selection of this Kiyosu site once again as the stage for a council of senior retainers also carried the meaning of returning to the birthplace of the Oda clan, centered on Owari and Mino, to deliberate on the succession system. The conference was held at Kiyosu Castle in Owari on the 27th day of the 6th month of Tenshō 10 (July 16, 1582). Four men who held the status of senior retainers attended directly: Shibata Katsuie, Niwa Nagahide, Hashiba Hideyoshi, and Ikeda Tsuneoki. The other senior retainer, Takigawa Kazumasu, had been defeated by the Later Hōjō at the Battle of Kanagawa in the Kantō region, and his return to Kamigata was delayed, so he could not take part in the conference. Nobunaga's sons Oda Nobukatsu and Oda Nobutaka, along with the allied lord Tokugawa Ieyasu, are said to have exchanged written oaths entrusting the decision to the four senior retainers. It is also pointed out that the conference proceeded without Takigawa Kazumasu, who had originally held considerable weight within the Oda clan, and that as a result the influence of the attending senior retainers, such as Shibata Katsuie and Hashiba Hideyoshi, was relatively heightened.

The Succession Debate — Backing Sanbōshi

The greatest focus of the conference was who would succeed Nobunaga. Although Nobunaga already had several adult sons, according to the traditional account, his second son Oda Nobukatsu and third son Oda Nobutaka each asserted their claims to the headship and came into conflict, and Shibata Katsuie backed Nobutaka. Hashiba Hideyoshi, however, supported neither Nobukatsu nor Nobutaka and is said to have argued that Sanbōshi (later Oda Hidenobu), the son of the late Oda Nobutada who was then three years old, should be installed as successor. Hideyoshi's influence was considerable, owing to his prestige from defeating Akechi Mitsuhide at Yamazaki, and Sanbōshi's succession was decided over Katsuie's opposition. More recent research has suggested that Sanbōshi's succession was already a settled course, and that the substantive point of contention at the conference was instead who would serve as his deputy and guardian (kōken) until he came of age. Whichever account is correct, the result was that Sanbōshi inherited the headship of the clan, Nobukatsu and Nobutaka became his guardians, Hori Hidemasa served as his tutor, and a system was established in which the four senior retainers gave support.

The Redistribution of Territory

Together with the decision on the successor, the redistribution of the Oda domains was also settled. Nobukatsu inherited Owari Province and Nobutaka inherited Mino Province, respectively, and Hashiba Hidekatsu, Nobunaga's fourth son who had been adopted by Hideyoshi, was given Tanba Province. Shibata Katsuie was confirmed in his home domain of Echizen and, in addition, received Nagahama Castle, Hideyoshi's former holding, along with three districts of northern Ōmi totaling 120,000 koku. Niwa Nagahide, confirmed in his home domain of Wakasa Province, had two districts in Ōmi added, and Ikeda Tsuneoki had three districts in Settsu Province added. Sanbōshi was assigned Sakata District in Ōmi Province and Azuchi Castle. Hideyoshi, in addition to his existing Harima and Tajima, was granted Kawachi and Yamashiro, and as a result, including the Tanba holdings of his adopted son Hidekatsu, his domain increased by 280,000 koku, reversing its size relative to Katsuie's domain. Meanwhile, the allied lord Tokugawa Ieyasu was taking advantage of the situation to advance into the former Takeda domains (the Tenshō Jingo War), and the Kiyosu decisions amounted to ratifying this.

In this way, the Kiyosu Conference did not merely decide the successor; it brought about a major reshuffling of the domain sizes of the powerful men within the Oda clan. In particular, Hideyoshi's surrender of his former domain of Nagahama to Katsuie in exchange for Kawachi and Yamashiro, key strategic locations near Kyoto, came to hold great significance, as it allowed Hideyoshi to take the initiative in the Kinai in later political developments. Against Hideyoshi, who held the key locations around the Kinai, Katsuie's home domain of Echizen lay in the Hokuriku region, and the geographical constraint that it was difficult to move through the deep snows of winter also worked in Hideyoshi's favor in their subsequent conflict.

Result and Hideyoshi's Rise, and the Prelude to Shizugatake

As a result of the Kiyosu Conference, Hashiba Hideyoshi established a position that surpassed Shibata Katsuie both in influence within the Oda clan and in actual territory. Although Katsuie appeared to have preserved his standing as the foremost senior retainer, the substantive initiative had tilted greatly toward Hideyoshi. After the Kiyosu Conference, the confrontation between Hideyoshi and Katsuie gradually sharpened. Citing suspicions of treachery by Nobutaka and Katsuie, Hideyoshi overturned the Kiyosu decisions and moved toward installing Oda Nobukatsu as head of the clan. The confrontation between the two became decisive, and in Tenshō 11 (1583) their forces clashed in Ōmi Province at the Battle of Shizugatake. Hideyoshi's victory there destroyed Katsuie, and he then fully seized command of Oda authority, beginning the path that would lead to the establishment of the Toyotomi regime.

The Later Life of Sanbōshi (Oda Hidenobu)

Sanbōshi, installed as successor to the Oda clan at the Kiyosu Conference, grew up and took the name Oda Hidenobu. At the Battle of Sekigahara in Keichō 5 (1600), Ishida Mitsunari solicited his participation in the Western Army on the condition of an increase in domain of two provinces, Mino and Owari. Although he had originally intended to follow the Eastern Army, a delay in preparing his military equipment led him to accept this and raise an army on the Western side. On the 22nd day of the 8th month of that year, Hidenobu led 6,530 horsemen and fought the Eastern Army forces of Ikeda Terumasa and Fukushima Masanori at Yoneno, but he was defeated and retreated to his stronghold, Gifu Castle. After a siege lasting one day, on the 23rd day of the 8th month, Hidenobu was persuaded by Terumasa, surrendered, and opened the castle.

After his surrender, Hidenobu shaved his head and took Buddhist vows at Jōsen-bō in Kaminokano, Mino Province. His 130,000-koku domain in Mino was confiscated, and he was ordered into exile at Mount Kōya. However, because of lingering resentment over Nobunaga's earlier attack on Mount Kōya, he was initially not permitted to enter, and his disposition remained undetermined until the 28th day of the 10th month. On the 8th day of the 5th month of Keichō 10 (1605), Hidenobu came down from Mount Kōya and lived at its foot, but on the 27th day of that month he died at Mukaizoe at the age of twenty-six. With this death, the main line of the Danjō-no-jō house, the direct lineage of Oda Nobunaga, came to an end. Sanbōshi, who had been chosen as successor at the Kiyosu Conference and had even been given Azuchi Castle as a child, met his end within just twenty-odd years, having lost both his status as a daimyō and his house. This symbolized the decline of the authority of the main house in the late Sengoku period.

The Historical Significance of the Kiyosu Conference

The Kiyosu Conference is positioned in Japanese history both as a product of compromise among senior retainers to fill the power vacuum left by Nobunaga's death and as a conference that became an important step toward Hideyoshi's rise to control of the realm. Sanbōshi himself, the heir decided at the conference, never held real power amid the political developments that followed, and ultimately, in the wake of the Battle of Sekigahara, lost both his status as a daimyō and his house. While the Kiyosu Conference formally decided the "succession" of the Oda clan, it symbolized that real power had already passed into the hands of the senior retainers. The very fact that the vast Sengoku daimyō house, having lost its absolute head Nobunaga, was forced to settle its succession system and the distribution of its domains in a conference of just one day speaks even today to the speed and severity of the transfer of power in the late Sengoku period.